Heat-activatable delayed-setting adhesive products



Aug. 26, 1952 TE MPE RA TURE c. M. WISWELL 2,608,543

HEAT-ACTIVATABLE DELAYED-SETTING ADHESIVE PRODUCTS Filed Sept. 26, 1950 o /'o 26 so 4 o 50 6 0 70 a0 90 Z PLAST/C/ZEF? m Wqkfz/OM M ATTORNEYS Patented Aug. 26, 1952 E'NiTQ CE; 1

l HEAT-AGTIVATABLE DELAYED- SETTING i ADHESIVE PRODUCTS GharleslM. Wis'well, Westbrook, Maine, assignor to S. D. Warren Company, Boston, Mass a corporation of Massachusetts 7 y Application September 26, 1-950, Sei-ial No. 1S6,814,

, V t 1 This invention relates to heat-activatable adhesive compositions, i. e. materials which become adhesive only after heating, to sheet orother material coated, therewith, and to processes for producing such adhesive compositions and products, coated therewith; thefnovel compositions having, after heat has been applied and the composition cooled, a period during which they continue tobe adhesive and after'which they set permanently. I I

Broadly speaking heat-activatable adhesive compositions are old, such materials having been used to stick together two substances, erg. two sheets of papen'under the combined action of heat andpressure. Adhesive materials for such use are commonly referred to simply as being heat-sealing? In manycases; e. g. in applying a label to a glass container, it is iiiexpedie'nt to apply'heat while the two surfaces are in con tact. "Accordingly, simple heat-sealing composi tions are not satisfactory for use in such cases; More recently, however, heat-activata'bl'e adhesive compositions have been developedywhich, whenonceactiyatedpr fused'byheat and allowed to cool, remain adhesive] thereafter for aperiod of greaterjor less extent; Sheet material, c. g. a paper label, coated with suchaheat-activatable -adhesive composition will possess,*after the said composition has been heat-activated, and for las long as the tackiness .oradhesiveness persists, many or allor the advantages of an ordinary pressure sensitive. coated" sheet but at the same time avoids thelexpense and incom venicnce attendant upon: the use of a protective or carrier sheet to prevent the adhesivesheets stickingto other objects or to each other before they are used. l i l i One prior art methodof obtainingna heat activatable adhesive coating on sheet material has been to apply first to said, sheet material a coating of hard, non-crystalline; potentially adhesive, material, e; g. resinous material, and then to apply over the potentially adhesive coating a coating or layer of solid crystalline plasticizern It is found, however, that such a sheet must be held for a considerable time at fusing temperature in order for the two layers to blend sufficiently to give satisfactory results; otherwise a film of the crystalline material remaining unblended on the surface may cause unsatisfactory 6 Claims. (01. zed-529.7)

adhesion iyvhen the sheet materialjisjlapplied to the surface to which it is expected to adhere; A-nother prior, art method comprises (1) grinding separately tofine particle size a hard; non -ferystalliiie potentially adhesive material and a solidjcrystalline plasticizer; (2), subsequently mechanically mixing the two powdered materials in an aqueous suspension which also contains some binding material to stick'the particles to a surface, on which they may be'coated; (3) applying the said aqueous suspension to the surface of SheetmateriaI as, a coating layer, and (4) drying the coating. Such a coating becomes adhesive whenproperly heated and remains. so for some time, but it is found that since the particle'sof crystalline 'plasticizer present have a sharp, melting point, that is, the plasticizer changes, quickly Tfrom-a hard solid to a thin liquid, the melted fluid plasticizer is apt to be absorbed by the sheet material unlessTthelsheet materialfused isgreaseproof and therefore imperyious' to the liquid plasticizerh Obviously're- "striction of the adhesive coating to use on greaseproof material is undesirable. If used on non-'- greaseprpof stockepartfof the relativel expensiveplasti'cizer may be lost by absorption and alsofmay act to transparentiz e the base sheet material.

' I have discovered that a satisfactory delaye actidnfadhesivemay be mad by fusing together a" non-crystalline adhesive substance and a crystalline plasticizer therefor and that on hardeningjthisfsingle fusion product may be ground anda'pplied ,to sheet material as a dispersion, and heating win become sticky and retain its stickiness for a considerable time, but on standfingj'williadhere firmly to another object. Since inmy n'ovelcomposi'tion the plasticiaer does not exist in the form of separate individualparticles but {is incorporated with the other component in each particle;.the' plasticizer does not fuse independently of the other component and hence is notrwasted' by being absorbedin thesheet material, nor does it tend to render the sheet material transparent.- i 1 The behavior of the heat-activatable adhesive products1of the invention made by fusing togetherresin andsolid crystalline plasticizer can ing drawing in' which. the; figure is a diagram of solubility, brittle line, and fluidity line curves.

In the figure the ordinates represent temperature, and the abscissas represent percentage composition by weight, ranging from zero percent plasticizer at the left of the diagram to 100 percent plasticizer at the right. The curves are drawn for mixtures of a particular resin and a particular plasticizer, namely, polystyrene having a molecular weight of about 9000 and tri (para tert.-butyl phenyl) phosphate. Similar curves can be drawn for any other combination of resin and plasticizer. Naturally curves for other combinations will not coincide exactly with the curves shown but the same general pattern will be observed in all cases. Hence the diagram may be considered typical for any fusion com bination of the invention.

When a resin and a solid plasticizer therefor of the type contemplated by the present invention are melted together in any proportion the result is a transparent melt having every appear-' ance of a true solution, i. e. a. molecular dispersion of solute in solvent. It appears that in this system the resin may be considered to be the solvent, and the plasticizer to be the solute. In the drawing the line ode may be considered the line of solubility, saturation, or permanent compatibility. At any temperature and composition above and to the left of line ode the plasticizer and resin are compatible, whereasbelow line cde there is presenta greater quantity of plasticizer than is permanently completely compatible 'With the resin, which sooner or later causes loss of transparency and development of cloudiness in the mixture. any melt cooled to the'line cde will become hard and brittle. Proper manipulation may bring about such separation and consequent hardening in a short time-almost instantly. Normally, however, molten mixtures of the resin andplasticizer may be cooled considerably below line ode and may be kept there in a fluid or semi-fluid condition for a considerable time before solidification occurs. While this super-cooled condition" exists the plasticizer and resin remain in a state of transient or meta-stable compatibility; upon aging for a greater or less period, however, a degree of incompatibility will developjresult ing in solidification and loss of transparency. The controlled use of this meta-stable compatibility i 'a characteristic of the process of the invention. Thus in general any mixture falling to the right of point d may by proper treatment be obtainedin. solid form at room temperature but when again reactivated byheat it may'remain in tacky, adhesive condition for some time before again becoming solid. When the plasticizer content is high, i. e. for mixtures approaching point b' on the room temperature line "ab the period of adhesiveness may be relatively short, say, a few minutes or hours; for mixtures slightly to the right of d the period of'adhesiveness may last for months.

Mixtures falling to the left of point (1 in. general do not exhibit the property of extended adhesiveness or delayed setting and consequently they are not useful according to this invention.

The line fd is the brittle line given by solutions of plasticizer in resin. It may be considered to represent the line at which'the resinous mass ceases to be easily friable and has softened sufficiently to be somewhat'flexible. The extension of line id to g is a line to which molten solutions of resin and plasticizer may be cooled while in the meta-stable state beforebecoming Given suiiicient time 4 brittle. The area above dg and below die, however, as explained above, is one of meta-stable equilibrium, because eventually, given sufficient time, the melt will solidify along line die. Line dg may therefore be considered a temporary line of brittleness, and line die the eventual or permanent line of brittleness.

Since a resin does not possess a sharp melting point there is a wide temperature diiference between the point at which a resin ceases to be brittle and the point at whichit is freely fluid. One way to obtain an arbitrary:fluidity temperature of a resinous material is to" sprinkle the powdered material along a heated bar having a known temperature gradient and then to observe the point on the bar at which the pow- ...dered resinous material becomes instantly transparent. The line hie represents fluidity temperatures obtained in the manner described. From 2' to e the fluidity line is substantially identical with the compatibility line, since the solid-fusion product will not melt until a temperature is reached at which the components are completely compatible.

lf'rom the foregoing description it is a parent that each particle obtained bypowdering any solidified fusion product falling below line fd Will consist wholly of a solid solution of plasticizer in resin and on melting will not exhibit the phenomenon of supercooling, since it does not contain sufficient plasticizer to cause incompatibility at the temperature in question. On-the other hand, every individual'particle obtained by finest mechanical disintegration of a solidified fusion product falling below line die will, on remelting, exhibit the phenomenon of supercooling, i. e. will become tacky on heating and retain the tackiness for sometime after cooling to room temperature, since it contains plasticiZer in excess of the amount whichwill form a solid solution at the temperature in question;

Reference to the drawing indicates' thatany composition falling to the right of point d on line ab will have a period of extended adhesive-1 ness at'room temperature for as lon' g ,'as'fthe state or meta-stable equilibrium'can ex st be fore incompatibility or excess plasticizer with the resin is effective to cause solidificationof the mixture. All compositions useful'under the invention are 3 characterized by possessing-such meta-stable compatibility; that is, the compositions contain a greater proportion of plasticizer than is permanently compatiblewith the resin. In case of the polystyrene resin andtri (para tert.-butyl phenyl) phosphate plasticizer; Erepresented by the curves of the diagram, the point d, to the right of which only meta-stable compatibility can exist, is approximately. at. 40 per,- cent plasticizer content. L

The minimum plasticizer content whichwill yield the desired extended period ofadhesiveness or delay in setting, or produce meta-stable compatibility in the mixture, will vary depending both on the particular plasticizers and the particular resins used. The followingTable. 1 lists various plasticizers'and resins which when combined posses complete compatibility at low plasticizer content and meta-stable compatibility at higher plasticizer content.*In the table the figures are the approximate percentagesfiofthe plasticizer in the compositions, by weight,'above which incompatibility at room temperature may begin, and these figures correspond to point d on the diagram of Fig. 1.

, TABLEMI.

. Resin Plast; Plast. Plast .Plast. .Plast. Plast. Plast. Plast; i V 1 z 3' I 4 5. 6 p 7 8.

Staybelite. -l 22 24 25 25 .27 27 Polypaler 32 35 36 36 40 WoodrosinAB 3O 33 -34 34 38 l 37 42 synthetics A 56 34 37 41 41 42 l 43 .,47 Polypale ester 10.. 89 1. 43 l 35 35 46 45 55 DOW.PSZ. 40 l l 40 40 40 40f I40 40 Nevindene R-3 41 "45 '47 47 52 51 58 Pentalyn G 41 l 45' .i 50- 46 52 51 67 synthetics A-52 45 49 51 51 56 55 63 i 3 I AYAO 40 40 preceding table the. materials mentioned may be identified as follows: Plasticizerl is acetanilid;

Plasticiaer is a meta-terphenyl sold..."as santowax Mf.by Monsanto Chemical Company.

Plastlcizer. 3. .is [.ortho-terphenyl Santow'aa 0. by Monsanto Chemical. Company.

Plasticizen l is diphenyl .phthalate.

Plasticizer. 5 is dicyclohexyl, phthalate sold as Plasticizer .71 is N-cyclohexyl -.parato1uene 5111-.

Chemical Company.

Plasticizer 8. istri (para tert.-butyl phenyl) V fona'midesoldas Sant'icizer IH'by Monsanto phosphate sold as Blastici'zer 7.7 by Dow Chemical Company.

Staybelite .is hydrogenated rosin sold by Hercules Powder Company. i p

Polypale, resin is polymerized rosin sold by HerculesiPowder Company.

o'd rosin AB is agndeldfwood rosin sold a by HerculesPowder "Company.

SyntheticsA56 is an adduct of maleic anhydrideand pentaerythritol esterof rosin sold by Hercules Powder Company.

P'olypalelister 10.is a glyceryl ester of poly-.

merized rosin sold by Hercules Powder Company; Dow PS2 is'a polystyrene of low (about 9000) molecular weight soldby Dow: Chemical Comevi'ndene R3 is' agrade of indene resin of M. P; 1510 C. sold by Neville Company.

Pentalyn G is a modified pentaerythritol esterfof rosin sold by Hercules Powder Company. synthetics A-'52, more recently sold byI-lei culesRowder; Company as .Pentalyn K is a pen'tae'rythritol ester of polymerized rosin acids.

AYAQF. is a low molecular weight polyvinyl acetate'hagvinga softening point of 45-60" C., SOldL by porajtiom It is apparent "from the foregoing table that in I all "cases except that of Plasticizer 77 metastable compatibility exists when the plasticizer conten'tds at 1east 60 percent, and in all cases it Carbide and Carbon Chemicals Corexists when the plasticizer content is ipercent.

Important stepsfin practicing the invention are (l) tdfuse together to a clear homogeneous fluid melt, readily'fusible resin and a quantity of solid crystalline plasticizer knownto be greaterthan that} permanently compatible with saidresin at room temperature, (2) to harden the melt until it is solid 'at-room temperature, i. e. until incompatibility has developed, and (3)to powder the solid -fusion product. The mass may be allowed to harden merely by cooling for a sufficient time; but if' it is desired to harden the melt more rapidly? the .molten mass may be stirred at a temperature. slightly below the lowest temperature at which complete permanent-compatibility can exist, whichis always somewhat below the melting point of the plasticizer and is repre sented by the line die of the diagram. For convenience of reference this lowest temperature-at which complete permanent compatibility. can

can readily be powdered.

When the solidifiedmass describedis crushed a or even ground to the finest particles distinguishable under a high powered microscope; all particles appear identical. The chief use of the compositions heating:

Compositions invention have valuable properties for useflin mary heat-sealing adhesives.

A very important use forthepowdered fusion.

' products of the invention is in aqueous coating- H compositions to be applied to paper orother sheet. material to form a heat-activatable adhesive coatingthereon whereby said paper or other sheetv materialmay readily be attached to.an-. other surface as desired. The problems involved in preparing and applying sucha coatingto sheet material are in general similar to those known in the art of; applying aqueous coating composi- I tions. When the powdered resinous fusion composition has once ,been wet with aqueous fluid,

it issurprising how greatly coating compositions. made therewith resemble ordinary clay coating As binders to bind the powder to thesurface coatedtherewith there may beused the identical binders commonly used in making.

clay coated papers, and in approximately the same r amounts. Theaqueous, compositions so made compositions.

may have. approximately the same percentage of compositions.

of the invention is to provide heat-softening, delayed setting adhesives which, after being heated, are :adhe-- sive. when pressure is applied and will retain such adhesiveproperties for some time following embodying the invention canin generalbe activated at somewhat lower terhpera tures. than those of the prior art; they need to be held at, the fusion temperature. for a shorter time;,and, in the case of paper coated with com positions of the invention. less adhesive material is lost by absorption into the paper, i It is likewise found that compositions} of the Ordinarily the powdered adhesive materialdeposited on a sheet from a water dispersion thereof will not adhere firmly to the sheet but may fall off during handling. Accordingly it is desirable to add a binder to the coating compositions as is done with clay coatings and the like, but the quantity of binder used is not particularly critical. It is in general found suflicient to bind 100 parts of powdered resinous matter if there is used from 4 to 10 parts of polyvinyl alcohol, dextrin, modified starch, solubilized, casein, solubilized soy protein, or animal glue, but it is preferred to use binders that are themselves resinous in nature, and which may even blend with-or at least be acted on by the molten plasticized resinous'material, since such binders interfere less with the heat-activation of the coating. g

Some binders of a resinous nature which are sometime's-usedin clay coatings and which have been found suitable for use to bind the'heatactivated resinous powder are various primary emulsions of emulsion polymerized styrenebutadi'ene copolymer, styrene-isoprene copoly- ,mers, butadiene-acrylonitrile oopolymers, copolymerized acrylonitrile and 'methyl 'acrylate, and the like, as well as natural rubber latex which in'general is not a satisfactory adhesive for ordinary clay coated printing paper. Of these, consideration of costs indicate the use of styrene-butadiene copolymers; a very satisfactory grade of the latter is the commercial product-sold by The Dow Chemical Company as No. 512K latex. Since a film of the styrene-butadiene copolymer may itself be rather soft and inclined to a tendency to block, it is advantageous to harden the binder somewhat by combining a harder polymer with the styrene-butadiene copolym'eri Excellent results are produced by using equal parts by weight of styrene-butadiene copolymer' and emulsion polymerized polystyrene of high (about 80,000) molecular weight. Such an adhesive may be referred to as a rubbery emulsion polymer of a'composition containing an ethylenically unsaturated monomer.

The emulsion polymerized elastomers mentioned above as desirable binding agents are sometimes called primary emulsions, indicating'that the dispersion has been formed by polymerization in situ, in contra-distinction to secondary dispersions formed by redispersion of agglomerated matter in an aqueous medium. Obviously dispersions of thepowdered resinous fusion products of the invention are secondary dispersions. The preferred coating compositions of the invention, therefore, comprise in an aqueous mediun 'a secondary 'clispersion'of a friable high-plasticizei 'resinous fusion product each particle of which contains solid plasticizer' in excessof that compatible with the resin, a dispersing agent, and a rubbery emulsion-polymer ofa composition containing an ethylenically unsaturated monomer, the latter constituent in 1 general not exceeding 25 percent by weight of the total solids present in the coating composi-.

tion.

The resin-plasticizer fusion products ofv the invention are ordinarily not wettable by water. Consequently some dispersing agent must .be used to disperse the powdered resinous masses in an aqueous medium. The particular type of dispersing agent used is not too important. Anionic dispersing agents such as soaps or resinates of ammonium, caustic soda, morpholine, ethanolamine, and the like, are very satisfactory; on the other hand, cationic agents, such as lauryl pyriisooctyl phenyl ether of polyethylene glycol. It is found in practice that it is advantageous to use as dispersing agent the product formed by treatving with ammonia, or other alkali such as caus- V tic soda, a resin of high acid number such the Synthetics A56 resin of Table I.

The following Example 1 describes one embodiment of the invention.

7 Example 1 A fusion was made of 75 parts by weight of diphenyl phthalate (a solid plasticizer), parts by weight of polystyrene of 6000 molecular weight (a resin) and 1' part by weight of solid commercial octadecanol (to aid in dispersing the product), a temperature of over 300 F. being ing reached. The melted mixture was poured on a cold slab to solidify. It was allowed to stand for six days and the solid product was then crushed; 100 parts byweight of the product was put into a ball-mill containing 75 parts by weight of water and 0.25 part by weight of tetrae sodium pyrophosphate; and the mixture was ball-milled for four hours. The mixture was then removed from the mill and mixed with 44.5

parts by weight of an aqueous emulsion of emulsion polymerized :40 styrene-butadiene copolymer. The resulting coating composition was applied by means of an air-knife coater to the reverse side of a one-side glossy coated commercial printing paper, the dry weight of coatin applied being about four pounds per 1000 square feet of surface coated. The coated paper was dried at room temperature. The final product.

was readily activatable by heat, and when so activated remained adhesive or tacky for several days. The activated product'was adherent to glass, metal and paper surfaces.

Preceding Example 1 was a satisfactory product, but the technique shown in following Example 2 is preferred over that of Example 1.

Example 2 waspoured upon a'cold metal slab, where it quickly became solid. The solidified fusion productwas then ground to a powder in a hammermill. Then 100 parts by weight of the powdered fusion-product was weighed out for'use.

A mixture was made of 3,75 parts by weight of water, .75 parts by weight of strong ammonia 3 water, and 1.5 parts by weight of the Synthetics A56 of Table I. This mixture formed a clear solution; its function was to act as a wetting or dispersing agent tohelp disperse the powdered resinous materialin aqueous medium. This solu- I tion was then added to a mixture of 77 parts by weight of water to which were added in succession 20 parts byweight of a 45 per cent solids emulsion of an emulsion polymerized of 60:40 styrene butadiene copolymer, followed by 24 parts by weight of a 10 percent solids emulsion of emulsion polymerized polystyrene ofhigh molecular weight. To this aqueous mixture, while 19 it was being well agitated, was then added the 100 parts by weight of the powdered fusion product mentioned above. The whole charge was put into a ball-mill and ground for several hours, the grinding action serving completely to disperse the resinousxpowder-in the aqueous medium as well as to decrease somewhat further the size of the particles of the resinous fusion product.

[if When the aqueous mixture was withdrawn I TABLE 3 .Indene' resin of M. P. 150 C- Polyvinyl acetate having asoftening point between .40 and 60 C. Polystyrene of molecular weight about 9000. Pentalyn- G fPolypale Ester 10 .Staybelite .Synthetics A-56 from theball-mill it was then applied by means 10 Kauri copal I of a conventional air-knife coating-machine to Mastic resin the uncoated side'of a commercial grade of claysa da r i fcoated label paper. The dry weight of coating Rosin r applied amounted to about four pounds per. Ester gums, or glyceryl esters of natural resins thousand square feet of surface coated; The 1 such as rosin or copal. a r'so coate w F. was. ssists.tartar of I r in setting or of' prolonged adhesiveness after ,Thefie Product w readlly by heat-wactivationmay, in the products of the in- R t dW n tu m m adhe' .vention, be widely varied byvariations in the slve pressurefsensmve coPdmon for several ratio of plasticizer to resin used. Likewise variah Th actlvated afiheslve paper was tions in: the length of the period of delayor lplle d .succ essfully to Various Surfaces lncludlng prolonged adhesiveness may "be glass, metal and regenerated cellulose She varying the" particular plasticizer and/or the T pr re s l 111 Example 2 can ,9 particular resin used. The following Table 4 used satisfactorily with any of-the other powdered shows a considerable range of delay periods high-plasticizer fusion products described herein. which may result from merely changing the par- Dispersing agents and primary emulsions of elasticular resin and/or plasticizer used in the tie adhesives other thanthose used in Example 2 fusion. I

TABLE 4 Example Plzlist. Plgst. Plgst. Relsin Rezsin .Regsin Raisin geelizay s5 5 24 hrs. 5 48 hrs. 5 Edays. 5 Gdays. 5 Qdays 4| 5 (In the foregoing examples the parts are by weight.)

can be used without greatly changing the results. I A solid plasticizer to be useful according to the invention .(1) must be completely compatible with the particular resin used at temperatures above the melting .point of the plasticizer, (2)

must be incompletely compatible therewith at TABLE- 2 I Acetanilide Dicyclohexyl phthalate Diphenyl phthalate N-cyclohexyl paratoluene sulfonamide N-ethyl paratoluene sulfonamide Tri (para tert.-butyl phenyl) phosphate The very many resins suitable for use include both synthetic resins that become readily fluid when fused as well as resins of vegetable origin both in their natural state or in modified condition. A few of the many suitable resins are listed in Table 3.

In the foregoing Table 4:

Plasticizerl is N-ethyl paratoluene sulfonamide.

Plasticizer 2 is tri (para tert.-butyl phenyl) phosphate.

Plasticizer 3 is N-cyclohexyl paratoluene sulfonamide.

Resin 1 is indene resin, M. P. 150 C.

Resin 2 is Pentalyn G.

Resin 3 is Polypale ester No. 10.

Resin 4 is Synthetics A-56.

Each example of Table 4 was prepared by makingqa fusion of the ingredients shown, cooling, and powderingthe mass after hardening there of. It is to be noted that] in the examples of Table 4 the proportions used are the same in all cases, the differencesbeing only in the particular plasticizers or resins used. In Examples. 3 and 7 the same resin is used in both cases, but different plasticizers are used. In Examples 5, 6 and '7 the same plasticizer is used in every case, but different resins are used.

It will be noted that each of Examples 3 to 7 in Table 4 shows use of 85 parts of plasticizer to 15 parts of resin. In each case, if the plasticizer to resin ratio is changed to about parts of plasticizer to 20 parts of resin the delay period will at least be doubled.

As has previously been pointed out, any composition of the invention which falls to the right of the point d on the diagram of Fig. 1 will be capable of exhibiting prolonged adhesiveness or delayed setting after having been heat-activated. The point d, depending upon the parthe powdered fusion products of Examples 3'to '1 nets are shown in following Table 5.

ticular resin-plasticizer combination chosen, may vary widely, as is shown in Table 1; and for any new combination of plasticizer and resin may be easily determined by experiment. The low limit of plasticizer content in the fusion products of 5 the invention may therefore be considered to be the percentage represented by the point (1 of the diagram for the particular,resin-plasticizer combination under consideration. vFor practical purposes the feasible upper limit of plasticizer content is 95 percent. Compositions of higher plasticizer content, and even the plasticizer alone as has been previously pointed out, will exhibit some degree of prolonged adhesiveness or supercooling after having beenfused; but such compositions are of no interest according to the invention because of the insignificant degree of adhesive strength which they possess.

From the foregoing it should be apparent that inclusive, previously set forth, may be incorporated in aqueous coating compositions with dispersing agents and binding material as described. in Examples 1 and 2. Other useful fusion prod- TABLE 5 Example 8:

80 Diphenyl phthalate 10 Polystyrene of mol. wt. about 9000 10 synthetics A-56 Example 9:

8O N-cyclohexyl paratoluene sulfonamide 15 Polypale Ester 10 5 synthetics A-56 Example 10:

80' Tri (para tert.butyl phenyl) phosphate 15 Pentalyn G 5 Synthetics A 56 Example 11:

80 Dicyclohexyl phthalate 1O Polypale Ester 10 v 10 Polystyrene of mol. wt. about'9000. Example 12:

85 N-cyclohexyl paratoluene sulfonamide 15 Polyvinyl acetate of softening point 50 C. Example 13:

50 Diphenyl phthalate 50 Staybelite resin (In the foregoing examples the weight.)

While the fusion product of the invention is particularly adapted for use in powdered form as an ingredient in aqueous coating compositions containing added binding material, nevertheless the solidified fusion product either before or after being reduced to powder had utility by itself, either for use in a hot-melt coating composition, or for sale as an intermediate product.

parts are by 12 "I claim:

1. Acoating composition which comprises'an aqueous dispersion of finely divided particles of a solid substance which is the solidified fusion product of resinous adhesive material with a quantity of a solid plasticizer in excess of that permanently compatible with the resin at roo temperature.

2 .A coating composition which comprises an aqueous dispersion of finely divided particles of a solid substance which is the solidified fusion product of resinous adhesive material with a quantity of a'solid plasticizer in excess of that permanently compatible with the resin at room temperature and a water-dispersible adhesive permanently compatible with the resin at room temperature and an elastomeric binder therefor, said coating being capable of being activated by application of heat to become adhesive and pressure-sensitive and, when once so activated, of remaining in adhesive and pressure-sensitive condition at room temperature for at least several minutes.

5. A coating composition which comprises in aqueous dispersion a potentially heat-activatable component comprising finely divided particles of a solidified fusion product of from to parts by Weight of N -cyclohexyl paratoluene sulfonamide and from 20 to 15 parts by weight, of resin, and a binding component comprising a rubbery emulsion polymer of a composition containin an ethylenically unsaturated monomer, the dry weight of said rubbery polymer being not over 25 parts to each parts of said solidified fusion product, Y r

6. A paper product comprising a sheet of paper having on one side a heat-activatable coating comprising the dried residue of the coating composition of claim 5.

CHARLES M. WISWELL.

REFERENCES CITED UNITED STATES PATENTS Name Date Perry Feb. 15, 1949 Number 

1. A COATING COMPOSITION WHICH COMPRISES AN AQUEOUS DISPERSION OF FINELY DIVIDED PARTICLES OF A SOLID SUBSTANCE WHICH IS THE SOLIDIFIED FUSION PRODUCT OF RESINOUS ADHESIVE MATERIAL WITH A QUANTITY OF A SOLID PLASTICIZER IN EXCESS OF THAT PERMANENTLY COMPATIBLE WITH THE RESIN AT ROOM TEMPERATURE. 